Non-air-entraining mixer/dispenser

ABSTRACT

A mixer and dispenser is described which thoroughly and quickly mixes a fluid and catalyst without the occlusion of air. The combination mixer/dispenser is in the form of a syringe having a hermetic sealing arrangement including a rubber septum at the dispensing end, which syringe converts from a mixer to a dispenser by the simple use of a rigid spacer.

BACKGROUND OF THE INVENTION

It is often necessary in the bacteriological, pharmaceutical, surgicaland the like arts to thoroughly mix chemicals, for example, a fluid anda catalyst, in such a manner as to avoid any air entrainment. Thisinvention is directed to such an apparatus for mixing small amounts offluid and catalyst so as to obviate any air entrainment or contaminationof the contents during either the mixing or dispensing, and is animprovement upon the mixer/dispenser described in co-pending applicationSer. No. 913,066 filed on June 6, 1978.

It is the object of this invention to provide a simple and easy to useapparatus which performs the dual function of mixing and dispensingfluid without the entrainment of air.

It is another object of this invention to satisfy the foregoing objectwith a device that is easy to operate, low in cost, and which,therefore, may be disposable.

It is a still further object of the invention to provide an apparatuswhich satisfies the foregoing objects for a highly viscous fluid.

Still other objects, features, and advantages of this invention willbecome apparent upon a reading of the detailed specification whichfollows.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, reference is made to thefollowing drawings, taken in conjunction with the specification, inwhich:

FIG. 1 illustrates a non-air entraining mixer in accordance with theinvention.

FIG. 2 depicts an embodiment of a rigid spacer for converting the mixerto a dispenser.

DETAILED DESCRIPTION

FIG. 1 shows the non-air-entraining mixer, including a cylindrical body10 into which a reciprocating plunger assembly 12 is slidably mounted.

Plunger assembly 12 comprises a shaft 25 with piston 15 slidably mountedon shaft 25 between a knob 28 on the outer end of shaft 25 and a mixinghead 26 on the inner end of shaft 25. Spring 24 is mounted upon thatportion of shaft 25 which extends through and beyond piston 15, and actsin a conventional manner to urge piston 15 away from shaft knob 28. Theinner portion of shaft 25 extends through a seat 30 formed at the innerend of piston 15, on which an elastomeric sealing member 32, which hassealing functions on both shaft 25 and body 10, is snap fit. With theplunger assembly 12 removed from cylinder 10, piston 15 will normallyseat upon mixing head 26 (FIG. 1A). The presence of fluid in the cavity,however, will position the piston dependent upon the amount of fluid inthe cylinder, e.g., as shown in FIG. 1.

The delivery end of the mixer/dispenser has a Luer fitting or cap 11,which is a commercially available quick-connect utilizing helicalthreads 14 to interlock male and female mating cones 16 and 18 of thesyringe and cap, respectively. Luer fitting 11 is modified toaccommodate, in the recess at the end of the female cone 18, aTeflon-faced rubber septum 20 closing the aperture 22, which is locatedat the extreme end of the Luer cone. When Luer fitting 11 is mounted oncylindrical body 10, it forms a hermetic closure penetrable by ahypodermic needle through the septum for the injection of the catalyst.

The mixer will preferably be supplied pre-filled with a fluid which hasbeen de-gassed in a conventional manner in a vacuum chamber and thenpackaged with spring 24 in a compressed state (not shown). With thisarrangement, piston 15 will be riding firmly atop the fluid in thecylinder, and the mixing head 26 will be at the cylinder extreme nearthe delivery end.

Packaging under spring compression permits a positive internal pressureof spring against piston, thereby preventing air leakage inwardly duringshipment or storage. This is particularly important where the storage isat low temperature and where there is generally some fluid contraction.

When the material is needed, a catalyst (or any fluid to be mixed) isadded to the interior of the cylinder by injection from a hypodermicneedle inserted through septum 20.

Mixing is now accomplished by reciprocating the mixing head 26 back andforth, giving the shaft 28 a quarter turn upon each reciprocation. Theknob may be square to facilitate this action. FIG. 1A is a detail of themixing head 26, and as will be appreciated, reciprocation with the 90°rotation causes a thorough mixing of the catalyst and fluid. During themixing, sealing member 32 provides a seal between shaft 25 and piston 12through which it is moving. When mixing the fulids, spring 24 acts as aconstant return and the friction of piston to cylinder fit (whichincludes sealing member 32) maintains the piston in position.

Once the mixing has been concluded (the amount of mixing would generallybe determined empirically for any given fluid catalyst system), themixer may be converted to a dispenser. For this purpose the shaft knob28 is regressed until the mixing head 26 seats on the outer surface ofsealing member 32. Rigid spacer 34, shown in FIG. 2, is forced over thespring 24. Illustratively, spacer 34 is a split cylinder, fabricated ofaluminum, polycarbonate, or other appropriate material, having a lengthslightly less than the extreme displacement distance between shaft knob28 and the end surface 15' of piston 15. Upon being seated about thespring and shaft, spacer 34 is retained in position during use by, forexample, assuring that split diameter D is slightly less than springdiameter D'.

Now converted, Luer cap 11 is removed from the end of cylinder 10 andpressure on shaft knob 28 will be transmitted to the piston via thespacer. Sealing member 32 will provide the necessary seal so thatpressure on the cap will be transmitted directly to the fluid therebyforcing the fluid out of the cylinder end.

I have found that a suitable material for the piston and cylindercomponents is polypropylene, which is clear and permits visualization ofthe mixing process which is particularly helpful when the catalyst andfluid are different colors.

It will be appreciated by those skilled in the art that variousarrangements and modifications may be made in the embodiments of theinvention herein specifically disclosed, all without departing from thespirit and scope of the invention.

I claim:
 1. An apparatus for mixing and dispensing fluids without theocclusion of air comprising:a syringe-type cylindrical body having areduced portion at one end; a cap having a hypodermic needle pentrableseptum disposed in said cap; mating means between said reduced portionof said cylindrical body and said cap for hermetically sealing saidseptum to said reduced cylinder end; a plunger assembly insertable inthe other end of said cylindrical body, said plunger assembly comprisinga shaft, a mixing head disposed at one end of said shaft, a knobdisposed at the other end of said shaft, a piston reciprocally ridingsaid shaft between said head and knob for hermetically and slidablyfilling the spacing between said shaft and the cylinder walls, a springdisposed between said knob and said piston and urging said pistontowards said mixing head; and spacer means adapted for insertion betweensaid knob and said piston for locking the piston on said shaft, andconverting the mixing function to a dispensing function.
 2. Theapparatus of claim 1 wherein said mating means is Luer-type connectionand in which said reduced end portion of said body is conical.
 3. Theapparatus of claim 1 wherein said spacing means is a split rigid tubedimensioned to snap over said spring.
 4. The apparatus of claim 3 inwhich the split rigid tube has a length slightly less than the distancebetween the piston and the knob when said piston abuts said mixing head.5. The apparatus of claim 1 further comprising a single elastomericmember attached to said piston to provide a slidable sealing functionagainst both said shaft and said cylinder walls.
 6. In the apparatus ofclaim 1 in which the cylinder has contained therein a fluid, a methodfor assuring against the occlusion of air during storage and shipmentdue to volumetric changes in said fluid comprising:packaging saidapparatus with said spring compressed and said piston riding firmly atopthe fluid.